The description herein relates to producing a lesion in tissue, typically tissue that is part of the heart of a patient undergoing a cardiac procedure. To produce the lesion a catheter is inserted so that it contacts the tissue, and electromagnetic radiofrequency (RF) energy is injected from a catheter electrode into the tissue, causing ablation and production of a lesion.
Many relations for determining the size of the lesion have been proposed, and one of these relations is considered here. Those having ordinary skill in the art will be aware of other relations. As an example of a relation, the size S of the lesion is assumed to be proportional to a product of the force F applied by the catheter to the tissue, the electromagnetic power P dissipated during the ablation procedure, and the time T of the procedure. (Although the relation involves power P, the relation to lesion size is related to RF Generator Output Current (I), based on the following equation: P=G·I2, where G is a constant. This equation applies to all the following discussion.) Thus, an estimate of the size S of the lesion according to this assumption is given by equation (1):S=K·F·P·T  (1)
where K is a constant of proportionality and P=G·I2, where I is the RF Generator Output Current.
As is apparent from equation (1), an estimate of the size of a lesion given by the equation is linearly proportional to F, to P, and to T, since in the equation each of these variables is raised to the power of one. I.e., from equation (1) size S is a linear function of F, of P, and of T.
Documents incorporated by reference in the present patent application are to be considered an integral part of the application except that, to the extent that any terms are defined in these incorporated documents in a manner that conflicts with definitions made explicitly or implicitly in the present specification, only the definitions in the present specification should be considered.